Position detection method in touch panel and touch panel

Abstract

A position detection method that includes calculating a distance between 2 contact points in a first direction by measuring a potential of a first electrode in a state where a power supply voltage is applied to the first electrode and a second electrode is grounded, calculating a distance between 2 contact points in a second direction by measuring a potential of a third electrode in a state where a power supply voltage is applied to the third electrode and a fourth electrode is grounded, and correcting the distance between the 2 contact points in the first direction obtained by the potential of the first electrode in accordance with the distance between the 2 contact points in the second direction obtained by the potential of the third electrode.

What is claimed is: 
     
       1. A position detection method in a touch panel that includes a first resistance film having first and second electrodes provided one on each end in a first direction and a second resistance film having third and fourth electrodes provided one on each end in a second direction orthogonal to the first direction, the position detection method comprising:
 calculating a distance between two contact points in the first direction by measuring a potential of the first electrode in a state where a power supply voltage is applied to the first electrode and the second electrode is grounded; 
 calculating a distance between the two contact points in the second direction by measuring a potential of the third electrode in a state where a power supply voltage is applied to the third electrode and the fourth electrode is grounded; and 
 correcting the calculated distance between the two contact points in the first direction by multiplying the calculated distance between the two contact points in the first direction by a correction coefficient calculated from the calculated distance between the two contact points in the second direction, 
 wherein the correction coefficient increases as the calculated distance between the two contact points in the second direction increases, and decreases as the calculated distance between the two contact points in the second direction decreases. 
 
     
     
       2. The position detection method in a touch panel as claimed in  claim 1 , wherein the calculated distance between the two contact points in the second direction is corrected based on the calculated distance between the two contact points in the first direction obtained by the potential of the first electrode. 
     
     
       3. The position detection method in a touch panel as claimed in  claim 2 , wherein at a time of the correcting of the calculated distance between the two contact points in the second direction, the calculated distance between the two contact points in the second direction is multiplied by a correction coefficient that is defined in accordance with a space between the two contact points in the first direction. 
     
     
       4. The position detection method in a touch panel as claimed in  claim 1 , wherein the correction coefficient is a quadratic equation of the calculated distance between the two contact points in the second direction. 
     
     
       5. The position detection method as claimed in  claim 1 , further comprising:
 calculating coordinates of the two contact points in the first direction based on the corrected distance between the two contact points in the first direction. 
 
     
     
       6. The position detection method as claimed in  claim 1 ,
 wherein as the calculated distance between the two contact points in the second direction increases, the calculated distance between the two contact points in the first direction becomes shorter than an actual distance between the two contact points in the first direction. 
 
     
     
       7. A position detection method in a touch panel that includes a first resistance film having first and second electrodes provided one on each end in a first direction and a second resistance film having third and fourth electrodes provided one on each end in a second direction orthogonal to the first direction, the position detection method comprising:
 measuring a potential of the first electrode when the touch panel is contacted at two contact points by applying voltage to the first electrode without applying voltage to the third electrode; 
 measuring a potential of the third electrode when the touch panel is contacted at the two contact points by applying voltage to the third electrode without applying voltage to the first electrode; and 
 correcting a distance between the two contact points by correcting a distance between the two contact points in the first direction obtained by the measured potential of the first electrode by multiplying the obtained distance between the two contact points in the first direction by a first correction coefficient calculated from a distance between the two contact points in the second direction obtained by the measured potential of the third electrode, wherein the first correction coefficient increases as the calculated distance between the two contact points in the second direction increases, and decreases as the calculated distance between the two contact points in the second direction decreases. 
 
     
     
       8. The position detection method as claimed in  claim 7 , further comprising:
 calculating coordinates of the two contact points in the first direction based on the corrected distance between the two contact points in the first direction. 
 
     
     
       9. The position detection method as claimed in  claim 7 ,
 wherein as the distance between the two contact points in the second direction increases, the distance between the two contact points in the first direction becomes shorter than an actual distance between the two contact points in the first direction. 
 
     
     
       10. The position detection method as claimed in  claim 7 , further comprising:
 correcting the obtained distance between the two contact points in the second direction by multiplying the obtained distance between the two contact points in the second direction by a second correction coefficient calculated from the obtained distance between the two contact points in the first direction, wherein the second correction coefficient increases as the calculated distance between the two contact points in the first direction increases, and decreases as the calculated distance between the two contact points in the first direction decreases. 
 
     
     
       11. A touch panel comprising:
 a first resistance film having first and second electrodes provided one on each end in a first direction; 
 a second resistance film having third and fourth electrodes provided one on each end in a second direction orthogonal to the first direction; 
 a control part; and 
 a storage part; 
 wherein in a case where the touch panel is contacted at two contact points, the control part is configured to 
 calculate a distance between the two contact points in the first direction by measuring a potential of the first electrode in a state where a power supply voltage is applied to the first electrode and the second electrode is grounded, 
 calculate a distance between the two contact points in the second direction by measuring a potential of the third electrode in a state where a power supply voltage is applied to the third electrode and the fourth electrode is grounded, and 
 correct the calculated distance between the two contact points in the first direction by multiplying the calculated distance between the two contact points in the first direction by a correction coefficient calculated from the calculated distance between the two contact points in the second direction, 
 wherein the correction coefficient increases as the calculated distance between the two contact points in the second direction increases, and decreases as the calculated distance between the two contact points in the second direction decreases, and 
 wherein the correction coefficient is stored in the storage part. 
 
     
     
       12. The touch panel as claimed in  claim 11 , wherein the storage part stores a correlation between the distance between the two contact points in the second direction and the correction coefficient. 
     
     
       13. The touch panel as claimed in  claim 11 , wherein the control part is further configured to calculate coordinates of the two contact points in the first direction based on the corrected distance between the two contact points in the first direction. 
     
     
       14. The touch panel as claimed in  claim 11 , wherein as the calculated distance between the two contact points in the second direction increases, the distance between the two contact points in the first direction becomes shorter than an actual distance between the two contact points in the first direction.